Expandable Unitary Quick Mount Abrasive Discs and Support Pad Therefor

ABSTRACT

The combination of an abrasive finishing device and a support pad therefor. The support pad includes circular plastic plates formed to define a depressed center. A fastening member permanently affixed to the abrasive finishing article is attached in such a manner as to form a depressed center section for the abrasive finishing article which is received within the depressed center section of the support pad.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/US06/008852, filed Mar. 13, 2006, which claims the benefit of U.S. Provisional Patent Application No. 60/662,710, filed Mar. 14, 2005 and U.S. Provisional Patent Application No. 60/680,756, filed May 9, 2007. The disclosures of the above applications are incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to abrasive finishing articles and, more particularly, to the combination of an abrasive disc support pad and a disposable abrasive finishing disc in which the securing member affixed to the disposable abrasive finishing disc is disposed within a depressed center so that the securing member is entirely below the surface of abrasive finishing particles contained on an abrasive disc.

BACKGROUND OF THE INVENTION

In the use of rotatably driven abrasive finishing articles and particularly coated abrasive finishing articles including non-woven material, such abrasive finishing articles are adapted for use on a wide range of air and electric powered tools. Traditionally, such an abrasive or non-woven material finishing article are discs removably attached by way of a support pad assembly to a power tool. When the support pad assembly is rotated, the disc rotates with it permitting the moving abrasive disc surface to effectively finish the surface of a work piece. A variety of hub structures have been used in the prior art to secure the abrasive finishing discs to the power tool.

The earliest and very common of such structures includes a support pad having a reinforced central aperture arranged to be engaged over the threaded end of a rotary shaft of the power tool. The abrasive finishing disc is placed on the flat surface of the pad and a flanged nut is turned down onto the threaded end of the rotary shaft protruding through the disc. When the nut is tightened, the flange lays flush against the abrasive surface of the disc and clamps the disc to the support pad.

This traditional mode of attaching the abrasive finishing disc to the rotary power tool has two major disadvantages. The first of these is that by engagement of the rotating finishing disc against the work piece a large amount of torque is imported to the hub which tends to tighten the nut onto the threaded shaft of the power tool making it quite difficult to remove the nut in order to replace the disc after it is spent and usually involves the use of tools. In many heavy industrial applications, such abrasive discs have to be replaced quite often. As a result, when considering the number of power tools which may be in use at any given time, there is an excessive amount of downtime necessitated by such disc replacement. A second disadvantage is that the flange of the nut extends above the surface of the abrasive material on the finishing disc and the workers using the disc must be quite careful to prevent the flange on the nut from engaging the work piece which, in most cases, would impart damage to the work piece. Such severely limits the surface area of the abrasive finishing material on the abrasive finishing disc which may be used in finishing the work piece.

To overcome these problems, abrasive finishing discs were developed wherein a fastener was adhesively secured to the back surface of the abrasive finishing disc. One such fastener included a raised boss having a central aperture whose rim is turned inward and shaped to form a screw thread (referred to as a type R fastener) which receives the threaded end on a molded rubber support pad. Another such fastener is a threaded stud which is received by a female thread disposed in a molded rubber support pad (referred to as a type S fastener). These structures are allowed the user to attach and remove the abrasive disc to the support pad rather quickly. The necessity of utilizing adhesive materials to secure the fastener to the abrasive finishing disc obviously increased the manufacturing costs both as a result of the increased amount of material and labor.

In view of the foregoing disadvantages of the prior art, it is desirable to provide a support pad and a disposable abrasive finishing disc which includes a structure such that the device for attaching the disc to the support pad is disposed in a depressed center section of the abrasive disc in a manner such that it is entirely below

w the surface of the abrasive material. The support pad must also include structure for receiving the attaching apparatus secured to the abrasive disc so that it is capable of receiving the depressed center portion of the abrasive finishing disc. It is also desirable that the disc and the fastening member secured thereto be formed in such a manner that the disc can be disposed of when the abrasive material has been used. It is also desirable that the abrasive finishing disc may be quickly and easily removed and a new disc attached without the necessity of utilizing tools and without the attachment of any external adapters or other devices to accomplish that purpose.

SUMMARY OF THE INVENTION

The combination of an abrasive disc support pad and a disposable abrasive finishing disc comprising a support pad which includes at least one flat circular plate formed to provide a depressed center along with a support base having an outwardly extending flange to seat against the plate, a body having an internally threaded barrel and a base ring which extends outwardly and downwardly to form a cup shaped member adapted to receive and/or form the depressed center of the plate along with an abrasive finishing device with includes a circular disc of abrasive finishing material defining a depressed center and a fastener member formed of malleable material secured to the circular disc by upsetting a portion of a shaft extending therethrough to permanently secure the circular disc between a flange and the upset shaft with the flange entirely disposed below the surface of the abrasive finishing material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation in cross-section of the combination of an abrasive disc support pad and a disposable abrasive finishing disc;

FIG. 2 is a perspective view of an abrasive finishing disc constructed in accordance with the principles of the present invention;

FIG. 3 is a perspective view of a support pad of the present invention;

FIG. 4 is an exploded view partially in cross section of an abrasive disc and a fastening member constructed in accordance with the principles of present inventions;

FIG. 5 is a schematic illustration in cross-section showing the abrasive disc and fastening member assembled;

FIG. 6 is a schematic cross section of flat circular plate of the support pad;

FIG. 7 is a schematic cross section showing the plate of FIG. 6 formed to provide a depressed center; and

FIG. 8 is a schematic view in cross section of an alternative embodiment of the support pad of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an abrasive finishing disc having a fastener affixed thereto in such a manner that the abrasive finishing disc forms a depressed center such that the flange which holds the abrasive disc to a support pad is disposed completely below the surface of the abrasive finishing material which forms a part of the abrasive disc thereby maximizing the amount of surface area which is usable. The abrasive discs may be made of coated cloth or fiber or non-woven abrasive material as is well known in the art. The fastener device includes a shaft having male or female threads for attachment to a support pad. The support pad includes a depressed center area which cooperates to receive the depressed portion on the abrasive disc so that when the disc is fastened in place for use on the support pad, the fastener flange remains disposed below the abrasive finishing particle surface. The depressed center for the support pad is created by forming plates preferably formed from molybdenum disulfide filled nylon sheet but may also include other materials such as a lamination of molybdenum disulfide filled nylon and cloth supported neoprene plastic. Through utilization of such materials the plastic plates included as part of the support pad have a depressed center configuration when assembled on the support pad body. The degree of flexibility of the support pad may be determined by the number, thickness, diameter and the relative position of the plates contained in the pad to provide the desired amount of flexibility depending upon the particular application to which the abrasive finishing device is being applied.

By reference to the drawings, and more particularly to FIG. 1, there is illustrated schematically and in cross section an abrasive finishing article and a support pad therefor as constructed in accordance with the principles of the present invention. As is shown in FIG. 1, as abrasive disc 10 formed of non-woven abrasive material 12 has a fastener 14 secured in a centrally disposed opening thereof. As illustrated, the fastener 14 after being inserted into the opening is upset as shown at 16 to clamp the non-woven abrasive material surrounding the opening between the upset portion 16 and a flange 18 to thereby firmly secure the fastener 14 to the non-woven abrasive finishing article 12. The non-woven abrasive finishing article 12 is formed about its central opening so that there is provided a depressed center section 20. The utilization of the depressed center section 20 causes the surface 22 of the fastener 14 to be disposed totally below the surface 24 of the non-woven abrasive finishing article 12. By so positioning the surface 22 it will be clear to those skilled in the art that when the abrasive finishing article 10 is placed in use against the work piece the fastener 14 including the surface 22 does not contact the work piece. The fastener 14 includes a shaft 26 having externally disposed male threads 28 thereon for fastening the abrasive finishing article 10 to the support pad 30. The support pad 30 includes a body 32 having an internally threaded bore 34 which is adapted to receive the threaded shaft 26 of the fastener 14 at one end thereof and to receive a drive member such as an arbor which is in turn, affixed to an air or electric power tool to rotate the finishing article 10 against a work piece. Alternatively, the shaft 26 may be formed with female threads which receive a male threaded member in the support pad. It should also be understood that the bore 34 may be altered to receive discs having the prior art type S fasteners secure thereto. Such renders the support pad of the present invention more versatile and capable of being used with the abrasive disc of the present invention and prior art abrasive discs. The body 32 includes a plate retaining flange 36 extending radially outwardly from one end thereof. Positioned against the flange 36 is a circular plastic plate 38 upon which the non-woven abrasive finishing article 12 rests when the abrasive finishing disc is affixed to the body 32. If desired, a plurality of such plates may be utilized and as illustrated in FIG. 1, there is an additional plate 40 disposed on top of the plate 38. It is of particular importance to note that the plates 38 and 40 are formed about centrally disposed openings thereof in such a manner as to provide a depressed center 42 into which the depressed center section 20 of the abrasive finishing article 10 fits when it is secured to the body 32. Such construction further assures that the surface 22 of the fastener 14 is disposed at all times below the operational surface 24 of the abrasive finishing article 10. The plates 38 and 40 are preferably made of molybdenum disulfide filled nylon sheet material but may be made of other materials including a lamination of molybdenum disulfide filled nylon and cloth support neoprene. In any event, the material which forms the plates 38 and 40 is such that when they are formed to provide the depressed center 42 they retain that shape. After the plates are assembled against the flange 36 a base ring 44 is press fitted over the surface 46 of the body 32 to retain the plates 38 and 40 securely in place against the flange 36. As noted, the base ring 44 is constructed to have an upwardly extending peripheral rim 45 which forms a recess into which the depressed center sections of the plates 38 and 40 fit. The depressed center sections of the plates 38 and 40 may be formed upon assembly of the base ring onto the body or alternatively, may be pre-formed.

The structure of the support pad 30 as illustrated in FIG. 1 is such that the flexibility of the support pad is fixed and is determined by the diameter and thickness of the plates 38 and 40 as well as the number of such plates used. It will be understood by those skilled in the art that if a single relatively thin plate such as that shown at 38 is utilized there will then be provided a maximum degree of flexibility to the support pad. As the plate is increased in thickness or as additional plates are added, the flexibility of the support pad is decreased.

FIG. 2 illustrates in perspective view an abrasive disc 48 which as shown is a surface conditioning disc. As is shown, the fastener 50 is affixed to the abrasive disc and includes threads as described above for affixing the disc to a support pad. A support pad 52 is shown in FIG. 3 and is constructed to provide the depressed center area 54 as above referred to. As is shown in 53, the support pad includes a plastic plate 56 which is secured to the body 58 by the base ring 60 as above described.

FIGS. 4 and 5 illustrate the manner in which the abrasive finishing article is constructed. As is shown, there is provided an abrasive disc 62 having a centrally disposed opening 64 therein. The disc 62 includes a coated abrasive finishing surface 66 thereon. Also illustrated is a fastener 68 which includes a disc retaining flange 70. A reduced diameter portion 72 extends upwardly from the disc retaining flange 70 and provides a surface around which the opening 64 of the disc 62 is positioned. The threaded shaft 74 extends upwardly from the reduced diameter portion 72 and as above described is used to affix the abrasive finishing disc to the support pad.

To form the abrasive finishing article and make it ready for use on a support pad the fastener 68 is inserted through the opening 64 until the flange is seated against the abrasive finishing surface 66. This combination is then inserted into an assembly fixture which is formed to have a cavity therein. The disc 62 is seated on the fixture with the surface 76 around the opening 64 disposed adjacent the cavity. A force is then applied as shown at F against the flange 70 to force the fastener into the cavity and against a member of the assembly fixture which will upset the upper port of the reduced diameter portion 72 as is illustrated at 78 in FIG. 5. That is, the fixture is designed in such a manner that the upper portion of the decreased diameter portion 72 of the fastener is caused to move outwardly and thereby clamp the area around the opening 64 of the disc 62 between the flange 70 and the upset portion 78 thereby securely and permanently affixing the fastener 68 to the disc 62. As is also illustrated in FIG. 5 when the force F is applied the area around the opening 64 of the disc 62 is formed to provide a depressed center 80 to the disc 62.

By reference now more particularly to FIGS. 6 and 7 there is illustrated the manner in which the plates 38 and 40 are formed to provide the depressed center portion thereof. As is illustrated in FIG. 6 a flat plate 80 preferably formed of molybdenum disulfide filled nylon sheet is provided and includes a centrally disposed opening 82 therethrough. The plate 80 is positioned within a fixture and a tool is applied to the surface area surrounding the opening 82 to cause the plastic material forming the plate 80 to become permanently deformed to provide the depressed center 84 as shown in FIG. 7. This deformation causes the plate surrounding the opening to have a curved profile so that a first surface 86 surrounding the opening is concave and a second surface 88 on the opposite side thereof surrounding the opening is convex. As above indicated, any number of such plates may be pre-formed and provided and stacked one upon the other to provide the desired flexibility. As is also indicated above, the thickness of the plates may be varied depending upon the desired flexibility. Alternatively, the flat plate 80, or a plurality of such plates, may be assembled on the body 32 (FIG. 1) and seated against the retaining flange 36. The base ring 44 is then press fitted over the exterior of the body 32. The rim 45 of the base ring presses the area surrounding the opening 82 downwardly to thereby form the depressed center portion having the configuration shown in FIG. 7. Thus, it will be understood by those skilled in the art that the depressed center section of the plates may be either pre-formed before assembly or may be formed during the assembly process without departing from the spirit or scope of the present invention as defined by the claims.

FIG. 8 illustrates an alternative embodiment of the support pad constructed in accordance with the principles of the present invention. The support pad of FIG. 8 may be utilized when it is desired to change the flexibility of the support pad. Such changeability is provided by providing the body 90 with external threads 92. A collar 94 having internal threads is then threaded upon the body 92 and is positioned against the base ring 96 to hold the plates 98 and 100 against the plate retaining flange 102. As will be readily understood by those skilled in the art, when the operator utilizing the support pad as shown in FIG. 8 wishes to change the flexibility thereof either to make it more or less flexible, the collar 94 may be removed, the base ring 96 may then be removed and an additional plate added or one of the plates 98 or 100 removed depending upon whether less or more flexibility is desired for a particular application.

Through the utilization of the molybdenum disulfide filled nylon (or other plastic material) plates, the resulting structure is lighter in weight than the support pads of the prior art. In addition to the variable flexibility thereof, the support pad as illustrated in the present invention may be rotated at a much higher rate of speed than that of the prior art molded rubber pads currently being used. If the prior art molded rubber pads are rotated at the same speed as the support pad of the present invention, they would immediately deteriorate and effectively explode throwing particles thereof into the surrounding area. As is illustrated and has been described in detail above, the fastener surface holds the abrasive disc from the abrasive surface thereof in such a manner that the retaining flange on the fastener is below the operating surface of the abrasive disc thus providing a larger useful area and also precluding contact of the work piece by the fastener. As above illustrated, the abrasive disc is held in place and is gripped both by the upset portion of the fastener against the disc retaining flange and in addition when the abrasive finishing article is affixed to the support pad the disc retaining flange captures the disc and presses it against the depressed center area of the body of the support pad.

There has thus been disclosed a support pad having a depressed center section which receives a complimentary depressed center section of an abrasive disc which is affixed thereto in such a manner that the fastening member is totally disposed below the operating surface of the abrasive disc to preclude contact thereof with the work piece. The abrasive finishing disc may be quickly and easily removed from the support pad and when spent may be discarded. 

1. The combination of an abrasive disc support pad and a disposable abrasive finishing disc comprising: (1) A support pad including: (a) at least one circular plate defining a centrally disposed opening therethrough and having first and second surfaces, (b) the plate surrounding said opening having a curved profile so that said first surface surrounding said opening is concave and said second surface surrounding said opening is convex to thereby provide a circular plate having a depressed center, (c) a support base including a body having an outwardly extending first flange engaging said second surface of said plate, said body defining a centrally disposed opening therethrough, (d) said opening adjacent said first flange defining a cup shaped recess for receiving a central portion of said abrasive disc, (e) a base ring surrounding said body to retain said at least one plate against said first flange; (2) An abrasive disc comprising: (a) a circular disc having abrasive finishing material on at least one surface thereof and defining a centrally disposed opening therethrough, the disc surrounding said opening being deformed to define a depressed center in said abrasive finishing material, and (b) a fastener member formed of malleable material including a shaft having a second flange extending outwardly from one end thereof, said second flange being received within said depressed center of said abrasive finishing material, said shaft adjacent said opening in said disc being upset to permanently secure said circular disc between said second flange and said upset portion of said shaft, said second flange being entirely disposed below a working surface of said abrasive finishing material, said shaft being threadably received within said centrally disposed opening of said body.
 2. The combination as defined in claim 1 wherein said at least one circular plate is a molybdenum disulfide filled nylon plate.
 3. The combination as defined in claim 1 wherein said at least one circular plate is a molybdenum disulfide filled nylon and cloth supported neoprene plate.
 4. The combination as defined in claim 1 wherein said base ring is press fitted to an outer surface of said body.
 5. The combination as defined in claim 1 wherein an outer surface of said body is threaded and which further includes a collar having an internally threaded opening therethrough and which is threadably received on said outer surface of said body for retaining said at least one plate on said body.
 6. The combination as defined in claim 1 wherein said base ring includes a periphery extending away from said base ring and engagement with said at least one plate.
 7. An abrasive finishing disc for use with a support pad having a depressed center and a threaded centrally disposed opening therethrough, said disc comprising: (a) a circular disc having abrasive finishing material on at least one surface thereof and defining a centrally disposed opening therethrough, the disc surrounding said opening being deformed to define a depressed center in said abrasive finishing material; and (b) a fastener member formed of malleable material including a shaft having a flange extending outwardly from one end thereof, said flange being received within said depressed center of said abrasive finishing material, said shaft adjacent said opening in said disc being upset to permanently secure said circular disc between said flange and said upset portion of said shaft, said flange being entirely disposed below a working surface of said abrasive finishing material, said shaft being threadably received within said centrally disposed opening of said body.
 8. A support pad adapted to receive an abrasive finishing disc having a fastener affixed centrally, said support pad comprising: (a) at least one circular plate defining a centrally disposed opening therethrough and having first and second surfaces; (b) the plate surrounding said opening having a curved profile so that said first surface surrounding said opening is concave and said second surface surrounding said opening is convex to thereby provide a flat plate having a depressed center; (c) a support base including a body having an outwardly extending flange engaging said second surface of said plate and defining a centrally disposed opening therethrough; (d) said opening adjacent said first flange defining a cup shaped recess for receiving a central portion of said abrasive disc; (e) a base ring surrounding said body to retain said plate at least one plate against said first flange.
 9. The support pad as defined in claim 8 wherein said circular plate is constructed of molybdenum disulfide filled nylon.
 10. The support pad as defined in claim 8 wherein said circular plate is constructed of molybdenum disulfide filled nylon and cloth supported neoprene. 